External mix air atomizing spray nozzles are known for their ability to control of liquid particle size and spray distribution by pressurized air, independent of the liquid flow rate. They also can be used with relatively low pressure air supplies, such as on the order of 15 psi, which can be generated from inexpensive blowers, rather than air compressors. However, such spray nozzles typically must be formed with intricate air flow passages which communicate through the spray nozzle to locations downstream of the liquid discharge orifice. Such passageways are expensive to manufacture, create pressure losses, and if not formed with precision and accuracy can result in burrs and passage misalignments that cause further pressure losses that detract from efficient operation of the spray nozzle. Hence, the pressurized air supply generated by low-pressure blowers sometimes is inadequate to enable effective liquid particle breakdown and direction. Moreover, while external mix air atomizing spray nozzles have been used for producing flat fan spray patterns, heretofore they have not been effective, at low pressures, for generating full cone liquid spray patterns with substantially uniform liquid particle breakdown.